A multi-institutional paper with authors from India, UK and the USA, focuses on laser shock peening without coating a high strength ultrafine bainitic steel to mitigating the fatigue failures for automotive and structural engineering applications. Laser pulse density of 2500 pulses/cm2 (75% overlapping) was optimised based on the induced residual stresses for employing the wide range of characterisations. The roughness and topographic results showed that surface roughening was controlled by tuning the laser pulse density. The High-Resolution X-ray Diffraction analysis confirmed the lattice misorientation resulting peak shift and the trend towards martensite phase transformations. The electron microscopic micro/nanostructure analyses revealed the grain refinement features such as nano-twins, micro shear bands and shear cells. The work hardening depth analysis indicates the significant enhancement in the mechanical properties. Completely reversed (R = −1) high-cycle fatigue tests extended the lifespan by an average of five times than the untreated. Also, it has potential to repair the structural components effectively. Congratulations to Prabhakaran Subramaniam from Vellore Institute of Technology, for his efforts on getting this published.
To access the paper please see the following citation and a link:
S Prabhakaran, S Kalainathan, P Shukla, V.K Kalainathan (2019), Residual Stress, Phase, Microstructure and Mechanical Property Studies of Ultrafine Bainitic steel through laser shock peening, Optics & Laser Technology, 115, 447 – 458.
Here are the highlights of the paper:
Low energy laser shock peening without coating enhanced the surface properties of ultrafine bainitic steel;
The martensite phase transformations trend and the lattice misorientation in the crystalline structure;
Grain refinement features such as nano-twins, micro shear bands;
The high strain work hardening enhanced mechanical properties